Parts of tools are often interconnected by push-on couplings by means of a polygonal coupling body on one part and a complementary counter-part on the other part of the tool. A typical example is the attaching of a socket matching the shape of the respective screw or nut, or the attaching of an extension bar to a ratchet. Other applications are the attaching of a sliding T-handle, an adaptor, a drive handle, a universal joint, a flexible handle, a speeder brace or a T-handle universal joint spanner. Mere push-on couplings are unsafe and can easily get loose. Therefore, coupling devices with locking balls are provided, which hold the parts of the push-on coupling, namely polygonal coupling part and complementary counter-part, together.
A tool, for example a ratchet, has a square, which is rotatable step-by-step through a ratchet mechanism by reciprocating a handle lever. A socket, i.e. a tool part having a shape matching the screw or nut to be rotated, is coupled with this ratchet. For adapting the tool to the respective screw or nut, this socket can be removed and can be replaced by a socket of the appropriate shape. The socket is locked by a locking ball. When the socket is to be removed, the locking ball can simply be pushed inwards by pulling the socket from the square. This may require considerable force, as also large and, thereby, heavy sockets have to be retained safely on the square. As the screw or nut often cannot be reached with the normal tool, extension bars or connecting tools such as universal joints or adaptors are required.
Push-on couplings with quick release are known. Usually, such push-on couplings have a spring-loaded ball on the square, the ball engaging a corresponding recess of a socket or the like pushed on the square and retaining the socket in axial direction. A release button is actuated for releasing the push-on coupling. Thereby, a mechanism is moved which permits the ball to be pushed into the square. Then the parts can be disconnected by easily pulling the socket from the tool.
DE 201 19 262 U1 shows such a push-on coupling with quick release. A polygonal coupling part is provided on a base body. The polygonal coupling part has a radial bore in one of its side faces. A ball is guided in the bore. A rod is guided in a longitudinal passage of the polygonal coupling part. The rod has a recess. The ball can partially be accommodated by the recess. Then, it is completely sunk into the polygonal coupling part. The rod is rotatable about its axis by a releasing element between two angular positions. In one of the angular positions, the ball is urged radially outwards, whereby interlocking of the two parts of the push-on coupling is caused. In the other angular position of the rod, the recess is aligned with the bore, whereby the ball can yield and does not impede the pulling the push-on coupling apart.
EP 0 747 174 B1 describes a push-on coupling for a socket extension bar. A slide is movably guided in a longitudinal passage of a polygonal coupling part. The longitudinal passage communicates with a transverse bore. A ball is guided in the transverse bore. The slide has a recess which, in one position of the slide, is adapted to accommodate the ball. A spring acts on the slide. The slide can be shifted by means of a knob guided in a further transverse bore, through an inclined surface and against the action of the spring, to a position, in which the ball is accommodated in the recess.
The prior art structures described above require complex parts and, therefore, can only be manufactured with considerable expenditure.
EP 0 861 140 B1 describes a quick release coupling device, wherein a slide is guided in a longitudinal bore of a polygonal coupling body, the slide being axially displaced by a pivotally mounted actuating knob against the action of a spring. The slide has a reduced-diameter section. This section, in one position of the slide permits accommodation of a ball which is guided in a transverse bore. Thereby, the locking is released. Also this arrangement is very expensive both with respect to the design and with respect to the manufacturing.
U.S. Pat. No. 4,962,682 discloses a releasable coupling device wherein a generally longitudinal passage contains a row of balls of which the last one is located in a radial section of this passage. The balls are supported on a spring-loaded release button, the last ball extending beyond the surface of the polygonal coupling body. By pushing the release button down, a circumferential groove of the release button gets into the range of the balls, so that the balls can yield axially and the last ball yields radially.
DE 197 44 865 relates to a tubular socket extension. The socket extension has a square at one end and a square recess at its other end. A rod extends centrally through the tubular socket extension and is guided in a longitudinal passage of the square. The rod has a tapering end within the longitudinal passage. A ball is guided in a transverse bore. This ball can be urged radially outwards for locking, for example, a socket, when the rod is moved in the direction towards the square. If a square, for example of a ratchet, is pushed into the square recess, the square presses on the end of the rod extending into the sqare recess and moves the rod against the action of the spring into a position in which the ball is urged radially outwards through the tapering end.
DE 197 58 493 C2 shows a socket extension rod with an actuating body, which is movably guided in a longitudinal bore of a polygonal coupling body. The actuating body is generally cylindrical with a conically tapering end within the longitudinal bore. A ball guided in a transverse bore can be urged radially outwards by the conical end of the actuating body. The other end of the actuating body is formed by a knob having a plane surface. A spring urges the actuating body away from the ball out of the polygonal coupling body. A cam mounted for rotation can press the actuating body forward against the action of the spring and, then, moves the ball through the conical end into a locking position.